Xbox/Playstation games, do they read data from the inside or the outside? Or is it random?

Just wondering if games have a certain way of reading the data that is put on them? Does the console read the data from the inner of the disc or the outer first? Or does it scan the CD/DVD to find the data as and when it is needed?

With a traditional DVD the data is read from the inner circle of the disc outwards towards the outer edge.

I can't think of any other possible explanation to suggest Xbox / PS discs are any different although I suppose it's possible either way

11th May 2015

Inner to outer.

12th May 2015

The XBox360 DVDs were reverse spiral, meaning that layer 0 was read from the hub to the edge of the disc, but layer 1 was read from the edge back to the hub.

The same reverse spiral technology (named Opposite Track Path) is used on blu ray discs. So the XBox One and PS3 & 4 All read track 0 from hub to edge and track one from edge to hub.

This link is for the BDROM Command Set manual. Page 14 explains Opposite Track Path.

The disc author arranges the data on the disc surface based on need for regular access, speed of access required, size of data being stored. Unlike when you burn a disc at home and it simple burns from hub to edge, when authoring a disc for video games, the publisher generally takes care over what is stored on specific areas of the disc. A process that I can only presume is mind boggling and tedious.